* {
    margin: 0;
    padding: 0;
}

.back-top {
    height: 100px;
    background-color: aqua;
}

.back-left {
    width: 20%;
    height: calc(100% - 100px);
    float: left;
    background-color: #d78a32;
    display: flex;
    justify-content: center;
}

.back-right {
    width: 80%;
    float: left;
    height: calc(100% - 100px);
    /*background-color: brown;*/
}

.back-left ul li, ol li {
    list-style: none;
    line-height: 30px;
}

.back-left ol li {
    text-indent: 1em;
}

.back-left ul li ol li:hover {
    background-color: brown;
}